Wednesday, March 08, 2006

Musing and Math

The Big Cat and I are sharing a can of peas and surfing the Internet (because everybody else has friends and I had three hot toddies at Kate's). BC is not so much eating his peas as batting them around on the kitchen floor, but I think he may have consumed one or two. If not, I'll find them all under the oven in a few months. We used to do this at our apartment in IB, only it was kidney beans and video games. Special K just chewed us out and left the room so she didn't have to witness such a frivolous waste of time and canned vegetables.

I have things to do, really. Just nothing I feel like getting after. Maybe I'll go to bed. Yeah, that sounds good. I read three chapters on Fluoridation today. I have words like hydrofluosilicic acid and gravity feed floating around in my head. No wonder I can hardly complete a sentence, much less make one up that would be enjoyable to read.

And now I've decided to tell you how to come up with the amount of fluoride (sodium fluoride) a hypothetical plant might use in gallons per day. You take your daily flow (for instance, 6 million gallons per day), multiply it by the desired dose (1.2 mg/L or 1.2 parts per million, either way), and divide the result by the concentration of flouride you're using (a solution of 20% fluoride, say). You're going to need 36 gallons of fluoride a day, and that's going to cost you.

Say you decide to fluoridate your water (despite the astonishing number of anti-fluoridation organizations whose pages you can access on the Internet, and no I don't know if they're right or wrong- all I know is I have fantastic teeth and no detectable adverse health effects to speak of after growing up drinking fluoridated water). You need to know how long it's going to take that fluoridated water to move through your plant. You need to calculate detention time! That's right. Say you have a sedimentation basin that's 200'x140' and 11' deep. That's 308,000 cubic feet. Multiply that number by 7.48 to find out how many gallons it holds (2,303,840). Do the same for your 12 filters that are each 10'x20'x8' (1,600 x 12 = 19,200 cubic feet, x 7.48 = 143,616 gallons).

So altogether your plant holds 2,447,456 gallons of water at any given time. Say you have a flow of 3.5 million gallons per day. Divide by 1,440 (minutes in a day) to get gallons per minute (2,430) and divide that number into your total capacity (2,447,456, remember?). Did everybody get 1007? Divide by 60 (minutes in an hour). It's going to take that fluoridated water 16.8 hours to move through your plant. You'd better be there when it does to check your fluoride level; send overdosed fluoridated water out into the distribution system and you're going to have some serious explaining to do.

One more thing, because I'm on a roll. This morning I had to check the dosage of polymer (Polyaluminum Chloride 8157) we're treating our water with. I timed the feed and got 110 milliliters. I multiplied that by 1.26 (specific gravity of 8157), multiplied that by 1440 (minutes in a day), divided that by 3785 (converts milliliters to mg/L or ppm) and divided that by our flow, which is about 1.8 million gallons per day. Anybody? 29.2 mg/L. Which is enough to handle the milky water coming in from the river, which is thawing open now. Do you know how much cow manure is in the water you drink before somebody bothers to take it out?

Like Bekah said
the other day when I mentioned how vile cows are: "I don't care; I love beef. I hope there's beef in heaven. Beef and chocolate." She has a point. And clearly, motherhood agrees with the woman.

3 Comments:

Blogger Shepcat said...

To quote Chevy Chase as Gerald Ford: "It was my understanding that there would be no math…"

I'm totally cheating off your paper come quiz time.

March 8, 2006 at 10:51 PM  
Anonymous christmas angel said...

"Bah, you morons!" to those anti-flouridation organizations! I'm almost 30 years old (in 21 days - OMG!!!) and have never had a cavity in my life...what the heck to they know? They can just bite me, though their teeth would break and then I would bite back and mine would not! Although, I must say that I'm so glad you (and others like you) can do the math because I don't really want adverse health effects from having too much flouride. It's all about the quantities, baby!

March 9, 2006 at 10:02 AM  
Blogger A said...

I didn't really think about the math when I took the job, but I'm finding it refreshing.

Exactly. I'm all for it. I think the long-term adverse affects weigh far less than the short-term benefits.

March 9, 2006 at 12:13 PM  

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